Blind Time and Frequency Synchronization in OFDM Based Communication

We present joint frame/symbol timing and carrier frequency offset estimation using the first data symbol in a frame, the first half of the first data symbol is identical to the second half in the time domain. Approximately maximum likelihood (ML) estimation is proposed for timing offset and a fractional part of the frequency offset based on both the first data symbol and its cyclic prefix (CP) in time domain. We also find a integer part of the frequency offset with virtual carriers in frequency domain. By the proposed method, the accuracy of the frame/symbol timing synchronization is definitely improved and the timing metric has a peak only at the correct start point of a frame. The performance of the proposed method is shown analytically and by simulation.